Iron, vitamin D, iodine, omega-3: how the most common nutritional deficiencies in children manifest and when analyzes are justified

Fast meals, processed snacks, time spent in front of screens and less and less outdoor movement have radically changed children's nutrition. The result: nutritional deficiencies that set in slowly and can go unnoticed for a long time. Iron, vitamin D, calcium, vitamin B12, zinc, iodine and omega-3 are among the most common deficiencies found in children, including in Romania. We explain what role each plays, what effects deficiencies can have on growth, immunity and cognitive development and, above all, in which situations medical tests are warranted.

Child nutrition isn't just about “eating something,” it's about getting all the micronutrients it needs for growth, immunity, cognitive function, and energy. Deficiencies appear when the diet is unbalanced, and fast meals contain many processed foods, snacks from bags. In addition, a lot of time spent in front of screens and less time outdoors can lead to the establishment of deficiencies of essential substances: iron, vitamin D, calcium, vitamin B12, zinc, iodine and omega-3 fatty acids. They often set in slowly and may go unnoticed until clear symptoms or developmental difficulties appear. In Romania, deficiencies of micronutrients such as iron and vitamin D are extremely common among children, especially in the case of children who have weight problems and in urban areas where exposure to the sun is reduced and diversified nutrition is limited, according to a 2024 study.

Iron helps the child's energy and concentration

Iron is one of the most common deficient elements in children, both here and globally. Iron deficiency is the leading cause of anemia in children and can affect cognitive development, energy and attention.

An insufficient level of iron in the blood can cause:

• paleness, easy fatigue and lack of energy,
• difficulty concentrating at school or in activities,
• growth slower than age average,
• poor appetite or sensitivity to exercise.

Iron is essential for the production of hemoglobin, the protein in red blood cells that carries oxygen. When children don't have enough iron, they are at risk of feeling tired even after light activities and have poor academic performance. In severe forms, iron deficiency leads to iron deficiency anemia, which is no longer just a problem of fatigue. In young children, severe anemia is associated with delayed cognitive and motor development, and in adolescents with tachycardia and very low exercise tolerance. Without treatment, behavioral disturbances and persistent learning difficulties can occur.

Fast meals or processed snacks (chips, sweet snacks) contain energy, but very little bioavailable iron. In addition, excessive consumption of cow's milk in young children can inhibit iron absorption and increase the risk of anemia.

What parents can do:
Include in your daily menus rich sources of iron: lean meat (chicken, turkey, beef), legumes (lentils, beans), spinach and other greens, fortified cereals. Combine iron-containing foods with sources of vitamin C (citrus fruits, bell peppers) to improve absorption.

Vitamin D and calcium – strong bones, healthy development

Vitamin D and calcium work together for bone and tooth development. Without enough vitamin D, the body cannot absorb calcium effectively, which in severe forms can lead to rickets, a disorder characterized by soft bones, leg deformities and bone pain.

In children, vitamin D deficiency can occur even if the diet contains nutrient-rich foods but insufficient sun exposure. Studies in Romania show that a significant percentage of children have low levels of vitamin D, especially in cities and in the cold season.

Symptoms can be subtle:

• mild muscle or bone pain,
• fatigue,
• low immunity (frequent colds),
• delayed growth.

The childhood spent more indoors, in front of the screens, the shorter time spent playing outdoors, limits the natural synthesis of vitamin D in the skin. Severe vitamin D and calcium deficiency can lead to rickets in young children and osteomalacia in older children and adolescents. Signs include persistent bone pain, lower limb deformities (X or bracket legs), delayed walking, minor trauma fractures, and marked muscle weakness. In adolescents, severe deficiency can affect bone mass accumulation, with increased risk of osteoporosis in adulthood.

What parents can do:
Encourage at least 15-20 minutes of outdoor time each day (especially in the morning). Include dairy products, fatty fish (salmon, sardines), eggs and fortified foods in your diet. If there are concerns or symptoms, talk to your pediatrician about getting your vitamin D levels tested.

Vitamin B12 deficiency, common in gluttons

Vitamin B12 is essential for the formation of red blood cells, the functioning of the nervous system and the development of the brain. The deficiency may occur more frequently in children on strict vegetarian diets, picky eaters or those with digestive problems.

The lack of this vitamin can cause:

• persistent fatigue, weakness,
• concentration and memory difficulties,
• irritability or changes in behavior,
• subtle long-term neurological symptoms.

Modern diets focused on processed foods or without meat and dairy without additional sources of B12 can contribute to deficiencies. Teaching the child to accept a variety of foods is a challenge in the context of preferences for convenient snacks. Without vitamin B12, megaloblastic anemia and neurological damage can occur. Severe signs include extreme fatigue, palpitations, tingling in the hands and feet, difficulty walking, balance problems, and memory and concentration problems. In young children, severe and prolonged deficiency can lead to neurological developmental delays, sometimes difficult to reverse if the diagnosis is late.

What parents can do:
Include foods rich in B12: eggs, dairy products, meat and fish. For vegetarian families, fortified cereals or consulting a doctor about supplementation may be helpful.

Zinc, useful for immunity and growth

Zinc is a mineral involved in immune system function, protein synthesis and wound healing. Deficiencies can lead to decreased appetite, slow growth, frequent infections, and skin or hair problems. Severe zinc deficiency is manifested by growth retardation, significant loss of appetite, repeated and prolonged infections, skin lesions that are difficult to heal, hair loss, and disturbances of taste and smell. In severe forms, chronic diarrhea and delayed puberty in adolescents may occur. The modern eating style, high in refined foods and low in whole foods, can lead to insufficient zinc intake.

What parents can do:
Include nuts and seeds, meat, legumes and whole grains in your child's diet to support adequate zinc levels.

Iodine, help with thyroid function and energye

Iodine is essential for normal thyroid function, which regulates metabolism, energy and brain development. Iodine deficiency can lead to fatigue, difficulty concentrating and stunted growth. Severe iodine deficiency affects thyroid function and can lead to hypothyroidism. Signs include severe fatigue, slow growth, cold intolerance, constipation, weight gain and, in some cases, enlargement of the thyroid gland (goiter). In children, severe and prolonged iodine deficiency is associated with impaired cognitive development, decreased IQ, and persistent school difficulties. In many countries, including Romania, iodized salt is the main source of iodine. Avoiding excess salt without iodized substitutes can reduce the risk of deficiency.

What parents can do:
Using iodized salt in home cooking and eating naturally iodine-rich foods (fish, dairy, eggs) can help maintain healthy levels.

Omega-3, the brain and emotional state

Omega-3 fatty acids (especially DHA and EPA) are important for brain development, eye health and mood regulation. Modern diets, low in fish and seeds, can leave children with low omega-3 intake. This deficiency was reflected in difficulties in concentration, memory or unstable emotional states. Severe omega-3 fatty acid deficiency can be associated with major difficulty concentrating, memory problems, emotional instability, increased irritability, and attention disorders. Some studies link very low omega-3 levels to delayed cognitive development, vision problems and increased inflammation, with long-term cardiovascular health impacts.

What parents can do:
Include omega-3 sources: fatty fish, walnuts, flaxseeds, and chia. If your child's diet doesn't include these foods regularly, talk to your pediatrician about safe supplement options.

When is it justified to go with the little one for tests. Quick Guide for Parents

Analyzes are not done preventively “blindly”. They are recommended depending on the context, dietary history, lifestyle and clinical assessment of the child, only on the recommendation of the pediatrician/family doctor. The interpretation of the results must be done by the doctor, because “borderline” values ​​can be normal or relevant only in certain combinations.

• Child who is constantly tired, pale, underachieving at school, or who “has no energy” even though he is getting enough sleep. Useful analyses: complete blood count, serum ferritin, serum iron (± TIBC), at the pediatrician's recommendation.
• A child who often gets respiratory infections, complains of muscle pain or spends very little time outside, especially in the cold season. Useful analyses: 25-OH vitamin D, serum calcium (possibly phosphorus and alkaline phosphatase if bone is suspected).
• Vegetarian/vegan child, very picky eater or with persistent digestive disorders (bloating, diarrhoea, constipation). Useful analyses: serum vitamin B12, blood count. Sometimes folic acid, depending on the clinical context.
• Child with very low appetite, who grows more slowly than average for age or gets repeated infections and has a hard time recovering. Useful analyses: nutritional assessment. Serum zinc (interpreted in clinical context, not isolated).
• Child who rarely eats fish, avoids dairy, is always tired and has difficulty concentrating without a clear cause. Useful analyses: TSH and FT4 for evaluation of thyroid function; assessment of dietary iodine intake.
• Child with attention difficulties, irritability, low cognitive performance, who consumes almost no fish or vegetable sources of good fats. Useful analyses: there are no recommended routine tests. The evaluation is done through dietary anamnesis and clinical context; possible discussion with the doctor about supplementation.
• Child overweight or with a predominantly processed diet (“eats a lot, but not nutritious”). Useful analyses: complete nutritional assessment; targeted analyzes according to suspicion (iron, vitamin D, B12).